Angelman SyndromePhase 3AspireNCT06617429
Phase 3 Efficacy and Safety Study of GTX-102 in Pediatric Subjects With Angelman Syndrome (AS)
A Phase 3 study testing GTX-102 in people with Angelman Syndrome, run by Ultragenyx Pharmaceutical Inc at 28 sites in 6 countries.
Trial summary
The primary objective of this study is to evaluate the effect of GTX-102 in cognitive function in participants with deletion-type Angelman Syndrome (AS). Read more about this study
- Who is it for?
- Ages 4 to 17 years
- Conditions the study is for
- Angelman Syndrome
- What is being tested?
- GTX-102
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 129 participants
- Where
- 28 sitesin 6 countries
- Study dates
- 3 Dec 2024to 30 Oct 2026
- Phase
- Phase 3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 4 to 17 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- Signed informed consent from parent(s) or legal guardian(s)
- Confirmed diagnosis of AS with genetic confirmation of full maternal ubiquitin-protein ligase E3A (UBE3A) gene deletion causing AS in the region of 15q11.2 q13
- Able to ambulate independently, or with assistance at the Screening Visit (note, a child whose primary means of mobility is by wheelchair is excluded from the study)
- Platelet count, prothrombin time / international normalized ratio, and partial thromboplastin time within 1.5x the normal limits at the Screening Visit
- Willing and able to comply with scheduled visits, drug administration plan, laboratory tests, and all study procedures, including LP procedure, MRI, and tolerating anesthesia without intubation
- From the time of informed consent through to at least 6 months after the final dose of GTX-102, females of childbearing potential who are sexually active must use highly effective contraception or abstinence. Males are able to participate if they agree to remain abstinent (refrain from heterosexual intercourse) or use acceptable contraceptive methods during the study and for at least 3 months after the final dose of GTX-102
Who cannot join
- Any change in medications or diet/supplements intended to treat symptoms of AS (eg, sleeping aids, antiseizure medications, supplements, dietary change including ketogenic or low-glycemic index diet, other) within the month prior to the Screening Visit (excluding weight-based adjustments)
- Any condition that creates an increased risk of unsuccessful LP
- Current or expected concomitant use of drugs that increase the risk of bleeding (eg, heparin, low molecular weight heparin, platelet inhibitors)
- Known hypersensitivity to GTX-102 or its excipients that, in the judgment of the Investigator, places the subject at increased risk for adverse effects
- Presence or history of any condition, lab abnormality, or infection, that, in the judgement of the Investigator, would interfere with participation, pose undue safety risk, or would confound interpretation of results
- Pregnant or breastfeeding or planning to become pregnant (self or partner) at any time during the study
- Use of any investigational product or investigational medical device within 6 months or 5 half-lives prior to the Screening Visit or any prior use of gene therapy or ASO regardless of duration since last administration
- Concurrent participation in any interventional study
Trial locations and contacts
28 sites in 6 countries.
28 sites in 6 countries
United States14 sites
Rare Disease Research
Atlanta, Georgia, 30329
Children's Hospital Colorado
Aurora, Colorado, 80045
The University of Texas
Austin, Texas, 78723
Boston Children's Hospital
Boston, Massachusetts, 02115
UNC Chapel Hill Pediatrics
Chapel Hill, North Carolina, 27599
Rush University
Chicago, Illinois, 60612
Carum Research Inc
Dallas, Texas, 75243
Rare Disease Research
Hillsborough, North Carolina, 27278
Children's Mercy
Kansas City, Missouri, 64108
Cedars Sinai
Los Angeles, California, 90048
Nicklaus Children's Hospital
Miami, Florida, 33155
Columbia University Medical Center
New York, New York, 10032
UCSD, Rady Children's Hospital
San Diego, California, 92123
UCSF
San Francisco, California, 94143
Spain4 sites
Hospital Universitario Parc Tauli
Barcelona, 08208
Hospital Sant Joan de Deu
Barcelona, 08950
Hospital Universitario Puerta de Hierro
Madrid, 28222
Hospital Universitario Virgen del Rocio
Seville, 41013
Germany3 sites
Universitaetsklinikum Hamburg-Eppendorf
Hamburg, 20251
University of Leipzig
Leipzig, 04155
Haunersche Kinderklinik
Munich, 80336
Japan3 sites
Nagoya City University Graduate School of Medical Sciences
Nagoya, Aichi-ken, 467-0001
Osaka City General Hospital
Osaka, 543-0021
Hokkaido University Hospital
Sapporo, 060-8648
Canada2 sites
McGill University Health Centre
Montreal, Quebec, H4A3J1
British Columbia Children's Hospital
Vancouver, V6H 3V4
Poland2 sites
Medical University of Gdańsk
Gdansk, 80211
Polish Mothers Memorial Institute
Lodz, 93-338
About this study
Official title: A Phase 3, Randomized, Double-blind, Sham-controlled Study Investigating the Efficacy and Safety of GTX-102 in Pediatric Subjects With Angelman Syndrome
The primary objective of this study is to evaluate the effect of GTX-102 in cognitive function in participants with deletion-type Angelman Syndrome (AS).
- Conditions
- Angelman Syndrome
- Being tested
- GTX-102, Sham-LP
- Keywords
- Angelman Syndrome
- Medical subject headings
- Angelman Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
GTX-102Drug
Also called apazunersen
antisense oligonucleotide
Sham-LPProcedure or surgery
Small needle prick on the lower back at the location where the LP injection is normally made
| Study group | Role | What they receive |
|---|---|---|
| GTX-102 | Experimental | Participants will receive GTX-102 via lumbar puncture (LP) during both the double-blind and open-label period Receives: Drug: GTX-102 |
| Sham-LP then GTX-102 | Sham comparator | Participants will receive sham procedure during the double-blind period and then will receive GTX-102 via LP during the open-label period Receives: Drug: GTX-102; Procedure: Sham-LP |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change from Baseline in Bayley-4 Cognitive Raw Score Without Caregiver Input at Day 338
Measured: Baseline, Day 338
Secondary outcomes (9)
Net Response in Multidomain Responder Index (MDRI)
Measured: Day 338
Change from Baseline in ABC-C Hyperactivity/Noncompliance Subscale Score at Day 338
Measured: Baseline, Day 338
Change from Baseline in Bayley-4 Receptive Communication Raw Score at Day 338
Measured: Baseline, Day 338
Change from Baseline in Angelman Severity Assessment (ASA) Sleep Rating Raw Score at Day 338
Measured: Baseline, Day 338
Change from Baseline in Vineland Adaptive Behavior Scales-3 (Vineland-3) Receptive Communication Raw Score at Day 338
Measured: Baseline, Day 338
Change from Baseline in Vineland-3 Expressive Communication Raw Score at Day 338
Measured: Baseline, Day 338
Change from Baseline in Bayley-4 Gross Motor Raw Score at Day 338
Measured: Baseline, Day 338
Change from Baseline in ASA Gross Motor Rating at Day 338
Measured: Baseline, Day 338
Number of Participants with Treatment Emergent Adverse Events (AEs) and Serious Adverse Events (SAEs), Severity of AEs and Relationship to Investigational Drug, Procedure, and Premedication
Measured: 2 Years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Sep 2024
- Study start3 Dec 2024
- Primary completion10 Jul 2026
- Study completion30 Oct 2026
Why it stopped: Lack of efficacy
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Angelman SyndromeStudies of the same condition, open and under way.
- More trials run by Ultragenyx Pharmaceutical IncThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 129 participants (actual)
Sponsor and investigators
- Lead sponsor
- Ultragenyx Pharmaceutical Inc
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Medical Director, Study director, Ultragenyx Pharmaceuticals Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06617429
- Sponsor's protocol ID
- GTX-102-CL301
- Other IDs
- 2024-512600-19-00
- Acronym
- Aspire
- Status last verified
- Oct 2026
- First submitted
- 24 Sep 2024
- Last updated
- 3 Nov 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 3, Randomized, Double-blind, Sham-controlled Study Investigating the Efficacy and Safety of GTX-102 in Pediatric Subjects With Angelman Syndrome
- ClinicalTrials.gov ID
- NCT06617429
- Acronym / sponsor ID
- Aspire / GTX-102-CL301
- Conditions
- Angelman Syndrome
- Keywords
- Angelman Syndrome
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Lack of efficacy
- Enrolment
- 129 participants (actual)
- Lead sponsor
- Ultragenyx Pharmaceutical IncIndustry (pharma, biotech, devices)
- Study start
- 3 Dec 2024 (actual)
- Primary completion
- 10 Jul 2026 (actual)
- Study completion
- 30 Oct 2026 (actual)
- First posted
- 27 Sep 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary objective of this study is to evaluate the effect of GTX-102 in cognitive function in participants with deletion-type Angelman Syndrome (AS).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| GTX-102 | Experimental | Drug: GTX-102Participants will receive GTX-102 via lumbar puncture (LP) during both the double-blind and open-label period |
| Sham-LP then GTX-102 | Sham comparator | Drug: GTX-102, Procedure: Sham-LPParticipants will receive sham procedure during the double-blind period and then will receive GTX-102 via LP during the open-label period |
Who may qualify
- Ages
- 4 to 17 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (6 listed)
- Signed informed consent from parent(s) or legal guardian(s)
- Confirmed diagnosis of AS with genetic confirmation of full maternal ubiquitin-protein ligase E3A (UBE3A) gene deletion causing AS in the region of 15q11.2 q13
- Able to ambulate independently, or with assistance at the Screening Visit (note, a child whose primary means of mobility is by wheelchair is excluded from the study)
- Platelet count, prothrombin time / international normalized ratio, and partial thromboplastin time within 1.5x the normal limits at the Screening Visit
- Willing and able to comply with scheduled visits, drug administration plan, laboratory tests, and all study procedures, including LP procedure, MRI, and tolerating anesthesia without intubation
Key exclusion criteria (8 listed)
- Any change in medications or diet/supplements intended to treat symptoms of AS (eg, sleeping aids, antiseizure medications, supplements, dietary change including ketogenic or low-glycemic index diet, other) within the month prior to the Screening Visit (excluding weight-based adjustments)
- Any condition that creates an increased risk of unsuccessful LP
- Current or expected concomitant use of drugs that increase the risk of bleeding (eg, heparin, low molecular weight heparin, platelet inhibitors)
- Known hypersensitivity to GTX-102 or its excipients that, in the judgment of the Investigator, places the subject at increased risk for adverse effects
- Presence or history of any condition, lab abnormality, or infection, that, in the judgement of the Investigator, would interfere with participation, pose undue safety risk, or would confound interpretation of results
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| GTX-102Also: apazunersenantisense oligonucleotide | Drug | GTX-102, Sham-LP then GTX-102 |
| Sham-LPSmall needle prick on the lower back at the location where the LP injection is normally made | Procedure or surgery | Sham-LP then GTX-102 |
Primary outcome
Change from Baseline in Bayley-4 Cognitive Raw Score Without Caregiver Input at Day 338
Time frame: Baseline, Day 338
9 secondary outcomes
Net Response in Multidomain Responder Index (MDRI)
Time frame: Day 338
Change from Baseline in ABC-C Hyperactivity/Noncompliance Subscale Score at Day 338
Time frame: Baseline, Day 338
Change from Baseline in Bayley-4 Receptive Communication Raw Score at Day 338
Time frame: Baseline, Day 338
Change from Baseline in Angelman Severity Assessment (ASA) Sleep Rating Raw Score at Day 338
Time frame: Baseline, Day 338
Change from Baseline in Vineland Adaptive Behavior Scales-3 (Vineland-3) Receptive Communication Raw Score at Day 338
Time frame: Baseline, Day 338
Change from Baseline in Vineland-3 Expressive Communication Raw Score at Day 338
Time frame: Baseline, Day 338
Change from Baseline in Bayley-4 Gross Motor Raw Score at Day 338
Time frame: Baseline, Day 338
Change from Baseline in ASA Gross Motor Rating at Day 338
Time frame: Baseline, Day 338
Number of Participants with Treatment Emergent Adverse Events (AEs) and Serious Adverse Events (SAEs), Severity of AEs and Relationship to Investigational Drug, Procedure, and Premedication
Time frame: 2 Years
Results and safety
The study was stopped early (reason given: Lack of efficacy). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Nov 2026.
- Ultragenyx Patient Advocacy WebsiteLink provided by the sponsor.
- Ultragenyx Angelman Syndrome (AS) Research Study OpportunityLink provided by the sponsor.
- Ultragenyx Transparency CommitmentLink provided by the sponsor.
- Individual participant dataSharing planned: No
Related trials for Angelman Syndrome
RecruitingPhase 3
BEACON - Phase III Clinical Study of Rugonersen in Angelman Syndrome.
Angelman Syndrome
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CHAMPION: A Study to Evaluate the Efficacy and Safety of Obudanersen (ION582) in Children and Adults With Angelman Syndrome (AS)
Angelman Syndrome
RecruitingObservational study
A Natural History Study of Angelman Syndrome
Angelman Syndrome, Neurodevelopmental Conditions
Active, not recruitingPhase 3
REVEAL: A Phase 3 Study of Obudanersen (ION582) in Angelman Syndrome
Angelman Syndrome
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Web Intervention for Parents of Youth With Genetic Syndromes (WINGS)
Telomeric 22Q13 Monosomy Syndrome, Tuberous Sclerosis
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Medical Director study director
Ultragenyx Pharmaceuticals Inc.
28 sites in 6 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing GTX-102 in people with Angelman Syndrome, run by Ultragenyx Pharmaceutical Inc at 28 sites in 6 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 28 sites in United States, Spain, Germany, Japan, Canada and 1 more country. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study was stopped early (reason given: Lack of efficacy). Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change from Baseline in Bayley-4 Cognitive Raw Score Without Caregiver Input at Day 338 (time frame: Baseline, Day 338). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Nov 2026.